Exploring The Outer Solar System With Humans

It appears typical
no consideration for:
http://plato.stanford.edu/entries/parenthood/
and a one way trip with terra-forming
what can you expect from a physics lab.

In the middle ages cathedrals used to take up to 300 years to build in a time when the human lifespan was quite a bit less than it is now. People set a goal that lasted generations. We can do it again if we want. Let us just question the assumption that anything has to happen in 40 years to be useful and focus on a vision. A probe to Alpha Centauri, about 4 light years, is possible technically for launch within my lifetime. It would report back in another person's lifetime. That may not be the best mission, but I wish we would return to dreaming big as we did in the 1960s.

OK, so according to APL what it takes to get to Jupiter and back in two years is a 20,000 TON spacecraft (already at escape velocity) with a nuclear reactor providing 100 MW of electricity.

What is the point of the rest of the article?

"The deleterious effects of GCRs ultimately limit possibilities of the human exploration of the solar system. Unless huge (approximately factor of 10) mass penalties are paid, round-trip human voyages are likely limited to ~5 years even if artificial gravity can limit the health effects of microgravity."

"Such a project is potentially achievable at the cost of at least 10% of the current world GDP. "

McNutt, Horsewood, Fiehler

So, before someone else says it ...

"When a distinguished but elderly scientist states that something is possible, he is almost certainly right. When he states that something is impossible, he is very probably wrong."

Arthur C. Clarke

Ed Griffith, a mission to alpha Cen that launches within our lifetime (optimistically 2030 for me) cannot arrive within another lifetime (by 2100). Our current technology doesn't enable those speeds, and our politics and economy don't either. So either the mission preparation must take hundreds of years or the duration must be several millennia, or both.

So Dr_Manhatten (BTW is that a misspelling of Manhattan?) you think it's much easier and can be done with something the size of, say, ISS? What about radiation protection? What about the lack of resupply ships? What about the delta-v needed for orbital injection and reboost toward home? It really adds up...

FallingWithStyle, it's a nice quote, but overused and often misapplied. Keep in mind 2 of the 3 are working engineers and McNutt is the PI of a mission that flew. So you should start with the assumption they DO have a good practical feel for it, and then test your own skill by looking for a possible mental cul-de-sac or two. I'd hazard a guess the main thing they don't know is what thruster technologies will be available and when. (Wouldn't we all like to know.) It is useful to point out, as they did, that humans don't have an indefinite shelf life in interplanetary space, and how that constrains mission design.

"Ed Griffith, a mission to alpha Cen that launches within our lifetime (optimistically 2030 for me) cannot arrive within another lifetime (by 2100)"

By another lifetime I did not mean the next lifetime, just another lifetime as we did when we built cathedrals in the middle ages.

"Our current technology doesn't enable those speeds, and our politics and economy don't either."

I also envisioned an unmanned probe. If you mean launching this year then our current technology is not there. If you mean an unmanned probe using a light sail, 20 years to develop, and a few centuries to get there I suggest the technology is easily obtainable. You may be right on politics, which is why I made the suggestion. Thanks for the thoughtful response.

"So Dr_Manhatten (BTW is that a misspelling of Manhattan?) you think it's much easier and can be done with something the size of, say, ISS?"

No, I don't think it is easy at all. I think that the majority of the paper is chasing things (like radiation protection, consumables per person, etc.) that are completely inconsequential compared to the engineering (and financial) challenges of the propulsion requirements.

I could think of many things that could be done with 10% of the world's GNP. As much as I think human surveys of the outer solar system are cool, it would not even be close to the top of the list. I just fail to see the point of the effort that went into the analysis. Surely scientists at APL have better things to do.

My basic problem with (and confusion about) this paper is that it goes to extreme lengths to demonstrate that even the most optimistic assumptions about technology and global economics tell us that human exploration of the outer solar system is not practical.

Well, thank you very much. So this says to me, why bother to try to develop high performance electric propulsion and low-alpha space nuclear power systems? That's not going to do the job. Just give up and hope space aliens give us warp drive some day.

I just don't know what the authors are getting at.